1. Field of the Invention
This invention relates generally to concrete tamping devices and, more particularly, to an engine-driven tamping machine which can be easily maneuvered to compress paving material over a broad path, or for compressing or tamping dirt or other material.
2. Description of the Background Art
Several variations of wheel movable tamping devices are heretofore known. Many of these devices mainly consist of an impactor plate adapted to contact the material to be compressed or tamped, and a means associated therewith to cause the impactor plate to vibrate. Other devices employ an eccentric drive shaft to reciprocate a tamping foot structure.
For example, U.S. Pat. No. No. 2,917,979 issued to Dening et al. on Dec. 22, 1959 discloses an engine-driven tamper which can be hand guided or driven, and which can tamp concrete with a rotary reciprocating motion. The tamping element is disc-shaped and rotates eccentrically. U.S. Pat. No. 3,534,669 issued to Judd on Oct. 20, 1970 discloses a hand guided, engine-driven tamper designed for tamping dirt in an open trench on both sides of a pipeline. The apparatus includes a pair of laterally spaced tampers supported on a movable carriage for rapid vertical reciprocating motion, and is supported by a pair of wheels which guide the support the entire apparatus. U.S. Pat. No. 3,386,353 issued to Wells on Jun. 4, 1968 discloses a hand guided, engine-driven tamper having a rectangular float plate attached to a vibrating mechanism. U.S. Pat. No. 3,453,940 issued to Berkhoudt et al. on Jul. 8, 1969 discloses an engine-powered tamper of the vibratory type, which is hand guided. Wheels are provide to move the apparatus from one site to another, but are not used to guide the apparatus when in use. Instead, the user guides the tamper while it is in its upstroke and the tamping shoe is off of the ground. U.S. Pat. No. 2,85,828 issued to Brown et al. on Oct. 21, 1958 discloses a tamper which is engine-driven and hand guided. Eccentric weights are used to carry vibration to an impactor plate which is used for tamping dirt, paving material, etc. U.S. Pat. No. 2,894,435 issued to Brown on Jul. 14, 1959 discloses a tamper of a similar design to U.S. Pat. No. 2,856,828, except that the impactor blade is replaceable. Eccentric weights are still used to cause vibration. U.S. Pat. No. 3,997,278 issued to Riedl on Dec. 14, 1976 discloses an engine-powered tamper which is hand guided and supported by means of laterally spaced wheels. A rocker-type shaft has tamper pads in a fore and aft plane which are caused to rock, or oscillate, to tamp surface material. U.S. Pat. No. 3,160,216 issued to Ormes on Dec. 8, 1964 discloses an engine-powered, hand guided tamper for use on roofs or other surfaces where it is necessary to remove surface gravel, slag, felt, etc. The apparatus includes a plurality of tamper elements which operate with a reciprocating motion.
However, so far as is known, no hand-guided, wheel movable tamping devices have been devised which provide a broad tamping screen which can be rapidly reciprocated in vertical movement and driven forward at variable speed controlled by an operator, and which provide for powering the wheels for self-propelled operation. Forward movement of other devices has generally depended upon the bouncing effect of internal weights as they are reciprocated in a drum, or upon an operator pulling the unit forward.
The present invention overcomes the deficiencies in the foregoing described devices. An operator controlled variable speed driving wheel is used to propel the unit forward, and the vertical reciprocating action of the tamping screen is applied to a wide surface area. This provides and efficient, effective device for tamping concrete or other paving material over a broad pathway.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.